Influenza represents one of the most serious and common pandemic/epidemic viral diseases of human populations. Rapid mutations and rearrangements of the viral genome allow the virus to evade host immune responses, making the frequent development of vaccines to new viral variants necessary. We have developed a new approach to immunization for influenza that combines a unilamellar liposome carrier with a recombinant protein expressing specific antigenic epitopes. The recombinant protein immunogen incorporates a conserved N-terminal sequence of the structural M2 protein prospectively constructed to represent a variety of influenza H and N subtypes. The antigenic component of the protein is fused to a water-soluble hydrophobic protein domain that facilitates efficient integration of the antigen to lipid bilayer membranes. The water solubility properties of the hydrophobic fusion protein allows for its isolation and purification using commercially viable preparative procedures. We have previously shown that a M2e-based influenza vaccine (L-IAVM2e1-HD) stimulates active protective responses in mice and the objective of our present proposal is to confirm that the L-IAVM2e1-HD vaccine will provide similar protective immunity in ferrets and non-human primates. Comparative evaluation of the L-IAVM2e1-HD vaccine in ferrets and non-human primates are important studies because: 1) the ferret is a widely accepted model for testing of influenza vaccine candidates prior to clinical testing and;2) the correlates of protective immunity are unknown for M2-based vaccines in higher animals and thus, the establishment of surrogate endpoints for monitoring protective immune responses will be essential for setting the criteria for clinical testing of other M2 vaccine candidates where evaluation of efficacy, i.e., as in the case of an avian influenza vaccine, will not be possible. We believe that testing of the LIAVM2e1- HD vaccine will demonstrate that it is a highly effective means of stimulating protective responses against a structural, conserved viral protein, thereby facilitating the development of a vaccine against influenza that would not be rendered ineffective by antigenic shifts and/or drifts associated with mutations of the influenza H and N surface proteins. Vaccines based upon recombinant protein technologies also offer the opportunity to rapidly and efficiently adjust to changes in the virus, either natural or man-made, to generate new vaccines as needed. Taken together, the attractive features of this vaccine technology are designed to provide a major improvement in our ability to respond to influenza infections and the potential use of influenza as a biological weapon. PUBLICE HEALTH RELEVANCE: The long range goal of this vaccine program is to develop a unique new approach to immunization against pandemic/epidemic strains of IAV that will provide protection from infection by a variety of different viral subtypes. This approach is based on the use of the N-terminal ectodomain segment of the Matrix 2 (M2e) protein as an alternative to the haemagglutinin (H or HA) or neuraminidase (N) antigens for vaccine development. Our central hypothesis is that the M2e recombinant fusion protein, when presented in a multimeric configuration as a liposomal complex, can be used as a human vaccine that will provide broader protection against infection by different H and N influenza subtypes. The underlying rationale guiding our hypothesis is that the M2e structural protein is highly conserved and thus, the development of a vaccine that is capable of stimulating active immunity to the N-terminal amino acid ectodomain segment would provide protection against infection by multiple strains of IAV. The studies proposed in this SBIR AT Phase I application are focused on demonstrating the ability of an M2e-based vaccine to stimulate protective immune responses against an H1N1 strain of IAV in ferrets and a non-human influenza primate model.